Hideki Kuramitz

University of Toyama, Тояма, Toyama, Japan

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Publications (73)176.61 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A sensitive visual colorimetry was proposed for the on-site determination of arsenic in drinking water supplied from ground water. The method was based on an advanced molybdenum blue (MB) colorimetry combined with enrichment technique using membrane filter. A portable device equipped with two attachments of a CaCO3-cartridge was used to eliminate interference from phosphate and a tiny membrane holder to retain the MB was proposed for on-site analysis. Ten mL of sample solution containing 0.1-0.4 μg arsenic was passed through the CaCO3-cartridge. The arsenic in the sample solution was converted into MB and collected on a membrane filter as an ion-associate with a cationic surfactant. The arsenic was determined visually from the color intensity of the filter using color chart made from standard solution. The sensitivity is sufficient to detect the concentration of 10 μg L-1 adopted by the WHO standard. The speciation analysis for As(III) and As(V) was also successfully performed. The proposed method was applied to several ground water samples, and the analytical results were well comparable with those obtained by HG-AAS.
    Analytical methods 02/2015; 7(6). DOI:10.1039/C4AY03021D · 1.94 Impact Factor
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    ABSTRACT: In this study, a peptide-1 (RNRCKGTDVQAW) constructing lysozyme was conjugated with an electroactive daunomycin in order to voltammetrically detect ovalbumin (OVA). Hetero-bifunctional cross-linking agents with four kinds of ethylene chains in differing lengths were used to bind the peptide-1 and daunomycin. After a cross-linking agent had reacted with an amino group of daunomycin, the compound was introduced into the peptide to the cysteine residue in the peptide using a pendant arm. The OVA was sensed via a change in the electrode response of the daunomycin moiety, based on the binding between the peptide and the OVA. The adsorption of the peptide probe on the electrode increased with increases in the ethylene chain. The binding constants between the peptide probes and the OVA, however, did not depend on the length of the chain. This was because the ethylene chain influenced the binding. When the peptide and the daunomycin were bound using N-(6-maleimidocaproyloxy) sulfosuccinimide, the electrode response of the peptide probe was the most sensitive from among the four cross-linking agents. The calibration curve of the OVA using the peptide probe was linear and ranged from 1.5 × 10−11 to 3.0 × 10−10 M. Furthermore, this method could be applied to the electrochemical sensing of the OVA in egg whites and in fetal bovine serum.
    Analytica Chimica Acta 02/2015; 857. DOI:10.1016/j.aca.2014.12.001 · 4.52 Impact Factor
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    ABSTRACT: Herein, we present a novel spectroelectrochemical fiber optic sensor that combines electrochemistry, spectroscopy, and electrostatic adsorption in three modes of selectivity. The proposed sensor is simple and consists of a gold mesh cover on a multimode fiber optic that uses attenuated total reflection (ATR) as the optical detection mode. The sensing is based on changes in the attenuation of the light that passes through the fiber optic core accompanying the electrochemical oxidation-reduction of an analyte at the electrode. Methylene blue and ferrocyanide were used as model analytes to evaluate the performance of the proposed sensor. The optical transmission changes generated by electrochemical manipulation showed a good linear relationship with the concentration and the limits of detection (3σ) for methylene blue and ferrocyanide at 2.0×10-7 M and 1.6×10-3 M, respectively. The sensor responses were successfully enhanced with an additional level of selectivity via an electrostatically adsorpted, self-assembled monolayer (SAM), which consisted of a silane coupling layer, a poly anion, and a poly cation. The improvement observed in the sensitivity of a SAM-modified fiber optic sensor was rather encouraging. The optimized sensor had detection limits (3σ) for 8.3×10-9 M of methylene blue and 7.1×10-4 M of ferrocyanide. The developed sensor was successfully applied to the detection of ferrocyanide in stimulated nuclear waste.
    Analytical Chemistry 01/2015; 87(4). DOI:10.1021/ac504321u · 5.83 Impact Factor
  • Kazuto Sazawa, Hideki Kuramitz
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    ABSTRACT: Soil enzymes play essential roles in catalyzing reactions necessary for nutrient cycling in the biosphere. They are also sensitive indicators of ecosystem stress, therefore their evaluation is very important in assessing soil health and quality. The standard soil enzyme assay method based on spectroscopic detection is a complicated operation that requires the removal of soil particles. The purpose of this study was to develop a new soil enzyme assay based on hydrodynamic electrochemical detection using a rotating disk electrode in a microliter droplet. The activities of enzymes were determined by measuring the electrochemical oxidation of p-aminophenol (PAP), following the enzymatic conversion of substrate-conjugated PAP. The calibration curves of β-galactosidase (β-gal), β-glucosidase (β-glu) and acid phosphatase (AcP) showed good linear correlation after being spiked in soils using chronoamperometry. We also performed electrochemical detection using real soils. Hydrodynamic chronoamperometry can be used to assess the AcP in soils, with a detection time of only 90 s. Linear sweep voltammetry was used to measure the amount of PAP released from β-gal and β-glu by enzymatic reaction after 60 min. For the assessment of soil enzymes, the results of hydrodynamic voltammetry assay compared favorably to those using a standard assay procedure, but this new procedure is more user-friendly, rapid and simple.
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    ABSTRACT: The sensitivity of the arc-induced long period fiber grating (LPFG) sensor was improved utilizing the double-pass configuration. The sensitivity in terms of transmission attenuation of the resonance wavelength for the double-pass LPFG configuration was better compared to the single-pass configuration when it was used to monitor the avidin–biotin interaction over a period of 60 min. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2766–2769, 2014
    Microwave and Optical Technology Letters 12/2014; 56(12). DOI:10.1002/mop.28701 · 0.62 Impact Factor
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    ABSTRACT: Tetrabromobisphenol A (TBBPA), a type of brominated flame retardant that shows endocrine disruption effects, has been identified in leachates from landfills. Iron(III)-porphyrins that mimic the active site of peroxidases have been shown to be effective in oxidizing halogenated phenols, such as TBBPA. In the present study, TBBPA was subjected to oxidation with potassium monopersulfate (KHSO5) using an iron(III)-phthalocyanine-tetrasulfonic acid (FePcTS), structural analogue of iron(III)-porphyrin, in the presence of humic acid (HA), a major component in landfill leachates. When TBBPA was oxidized using the above system, the levels of degradation and debromination increased with increasing pH in the presence of HA. Because of landfill leachates are weakly alkaline (around pH 8), oxidation products derived from TBBPA were investigated at pH 8. Approximately 48% of the bromine in the degraded TBBPA was incorporated into HA, and hydroxy-tribromobisphenol A was determined to be the major brominated intermediate in the HA fraction. In the iron(III)-porphyrin catalytic systems, the brominated intermediate incorporated into HA is mainly TBBPA, and no hydroxy-substituted bromophenols are found. Thus, the catalytic power of FePcTS is higher than that of iron(III)-porphyrin catalysts.
    Journal of Environmental Science and Health Part A Toxic/Hazardous Substances & Environmental Engineering 07/2014; 49(9):981-7. DOI:10.1080/10934529.2014.894810 · 1.14 Impact Factor
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    ABSTRACT: For this study, a new method was developed to electrochemically detect ovalbumin via its binding with the peptide-1(RNRCKGTDVQAW) in lysozymes. The peptide that exists at the C-terminal of a lysozyme was combined with ovalbumin. When an electroactive compound was introduced to the N-terminal side of the peptide through ethylene gycolbis(sulfosuccinimidyl succinate), the labeled peptide-1 served as a probe for the detection of ovalbumin. The electrode responses of labeled peptide-1 were measured after the labeled peptide-1 and ovalbumin were incubated in a 0.1M phosphate buffer (pH 5.6). As a result, the electrode response decreased as the concentration of ovalbumin increased. The detection limit of ovalbumin was 2.3×10(-11)M as estimated at 3-fold the standard deviation (3σ) (n=5). Because the steric structure of the peptide and some of the amino acid residues were related to the binding, we prepared a peptide-2, to which the N- and C-terminals of peptide-1 were alternated. The decrease in the response for the labeled peptide-2 was less than that for the labeled peptide-1. In addition, the peak current of a peptide-3, for which the D of peptide-1 was replaced with S, was hardly changed with or without ovalbumin. Therefore, it was clear that the binding was influenced by the steric factors and by the sequence of the peptide. However, a peptide-1 with bis(sulfosuccinimidyl) suberate was designed to investigate the hydrophobic influences on the probe. The change in the peak current was smaller than that of peptide-1 with ethylene gycolbis(sulfosuccinimidyl succinate), which was due to the hydrophobic properties of the alkyl chain between the peptide and the ovalbumin. The proposed method could be applied to the determination of ovalbumin in egg whites. Consequently, the concept becomes an electrochemical sensing method for proteins based on the protein-peptide interaction.
    Analytica Chimica Acta 06/2014; 834C:37-44. DOI:10.1016/j.aca.2014.05.003 · 4.52 Impact Factor
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    ABSTRACT: When peat forest fires happen, it leads to burn soil and also humic acids as a dominant organic matter contained in peat soil as well as the forest. The structure and properties of humic acids vary depending on their origin and environment, therefore the transformation of humic acid is also diverse. The impacts of the peat fires on peat soil from Central Kalimantan, Indonesia were investigated through the characterization of humic acids, extracted from soil in burnt and unburnt sites. The characterization of humic acids was performed by elemental composition, functional groups, molecular weight by HPSEC, pyrolysate compounds by pyrolysis-GC/MS, fluorescence spectrum by 3DEEM spectrofluorometer, and thermogravimetry. The elemental composition of each humic substance indicated that the value of H/C and O/C of humic acids from burnt sites were lower than that from unburnt sites. The molecular weight of humic acids from burnt sites was also lower than that from unburnt sites. Pyrolysate compounds of humic acids from unburnt sites differed from those of humic acids from burnt soil. The heating experiment showed that burning process caused the significant change in the properties of humic acids such as increasing the aromaticity and decreasing the molecular weight.
    Environmental Science and Pollution Research 05/2014; DOI:10.1007/s11356-014-2929-1 · 2.76 Impact Factor
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    ABSTRACT: To electrochemically detect concanavalin A (ConA), a new method was developed using mixed micelles between a non-ionic surfactant with a maltose moiety and electroactive daunomycin. The surfactants, in which the length of the alkyl chain was different, were n-decyl-β-d-maltoside, n-dodecyl-β-d-maltoside, and n-tetradecyl-β-d-maltoside. The measurement principle was due to the micelle breakdown caused by the binding between the ConA and maltose moieties. When ConA was combined with maltose moieties at a concentration of surfactant that was near the critical micelle concentration, the daunomycin that formed the micelles was moved to a solution from the micelles. As a result, the peak current of daunomycin increased as the concentration of ConA was increased. The mechanism was proposed using voltammetry, spectrometry, and gel filtration. The linear range using n-tetradecyl-β-d-maltoside was 2.0×10(-9) to 8.0×10(-8)M of ConA, and it was the most sensitive in the presence of the three surfactants. To examine whether selective binding took place, measurements with several proteins were carried out. The electrode responses of daunomycin were not influenced by the presence of 5.0×10(-6)M protein. Furthermore, this method could be applied to the determination of ConA in a serum, and to the measurement of sugar chains that can be combined with ConA on the cell surface.
    Analytica chimica acta 03/2014; 814C:55-62. DOI:10.1016/j.aca.2014.01.031 · 4.52 Impact Factor
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    ABSTRACT: Because ovalbumin was combined with lysozyme, a new method was developed to electrochemically detect ovalbumin via its binding with peptide contained in lysozyme. The measurement principle was based on the change of the electrode response caused by the binding between the peptide with an electroactive compound and ovalbumin.
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    ABSTRACT: A higher enrichment of organic pollutant, di(2-ethylhexyl) phthalate (DEHP) was found in estuary of Oyabe River and Jinzu River, Japan. Based on this, the distribution of DEHP between water and bed sediment was investigated as a model of organic pollutant through both the field investigation and laboratory experiment. The laboratory experiment was performed to examine the effect of seawater, organic matter in sediment and hydrophobicity (log K ow ) of organic pollutants. The result showed that salting-out effect due to the high salinity in seawater and organic matter in sediment contributed towards the increasing of DEHP distribution between water and sediment. Furthermore, the hydrophobicity of organic pollutant also enhances the distribution between water and sediment to a higher magnitude in the presence of seawater.
    SpringerPlus 08/2013; 2:422. DOI:10.1186/2193-1801-2-422
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    ABSTRACT: A micro-scale algal growth inhibition (μ-AGI) test using a common micro-plate based fluorometric detection was used to demonstrate the effects of humic substances (HSs) on the toxicity of tetrabromobisphenol A (TBBPA) and its oxidative decomposition products 2,5-dibromo-1,4-benzoquinone (2,5-DBBQ), 2,5-dibromohydroquinone (2,5-DBHQ), 2,6-dibromobenzoquinone (2,6-DBBQ), and 2,6-dibromophenol (2,6-DBP) to Pseudokirchneriella subcapitata. The EC50 values were: EC50(TBBPA) = 7 mg L−1, EC50(2,5-DBHQ) = 7 mg L−1, EC50(2,5-DBBQ) = 19 mg L−1, EC50(2,6-DBP) = 49 mg L−1, and EC50(2,6-DBBQ) = 13 mg L−1. The toxicity of the chemicals was slightly lower in the presence of HA. The toxicity of TBBPA decomposed by a biomimetic catalytic system consisting of iron (III) 5,10,15,20-tetrakis (p-sulfonatophenyl) porphyrin (Fe(III)-TPPS) and KHSO5 was also evaluated using P. subcapitata and Chlamydomonas reinhardtii.
    Toxicological and Environmental Chemistry 03/2013; 95(3). DOI:10.1080/02772248.2013.775290 · 0.72 Impact Factor
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    ABSTRACT: An improved molybdenum blue spectrophotometry using a soluble membrane filter and CaCO(3)-column was proposed for determining arsenic in drinking water supplied from ground water in the presence of phosphate. A 100 mL sample solution containing 0.5 - 10 μg arsenic was passed through a CaCO(3)-column to remove phosphate, arsenate (As(V)). Arsenite (As(III)) which was not retained on the column was oxidized to As(V). As(V) was converted into a heteropolymolybdenum blue anion. The blue anion was collected on a membrane filter as an ion-associate with n-dodecyltrimethylammonium ion by filtration. The filter was dissolved in 2 mL of 2-methoxyethanol. The absorbance of the solution was measured at 810 nm against a reagent blank. Total inorganic arsenic was determined by reducing As(V) to As(III) before the column treatment. The RSDs for 10 μg L(-1) of As(III) and As(V) were 2.9%. Phosphate 0.2 mg L(-1) (as P) and iron 0.1 mg L(-1) did not interfere with the determination of 10 μg L(-1) arsenic. The proposed method was successfully applied to ground waters.
    Analytical Sciences 01/2013; 29(1):67-72. DOI:10.2116/analsci.29.67 · 1.40 Impact Factor
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    ABSTRACT: The evaluation of forest fire severity and effect on soil is very important when discussing the damage to the environment. The purpose of this study is to evaluate the effect forest fires have on the soil color using the CIE Lab system. The color changes in four kinds of soil samples caused by heating at different temperatures were investigated. It was found that the Δa* and Δb* values drastically decrease when samples were heated over the temperature range from 200 to 250 °C, that is above the ignition temperature of volatile matter. The Δa* and Δb* values show a good linear negative correlation with the atomic ratios of H/C and O/C. The results obtained from this study indicate that the proposed method is able to evaluate the dehydration and decarboxylation of soil caused by forest fires. We demonstrated this method using soil samples collected from unburned and burned areas in Kalimantan, Indonesia.
    Analytical methods 01/2013; 5(11):2660. DOI:10.1039/c3ay26251k · 1.94 Impact Factor
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    ABSTRACT: Rainwater pollution with formaldehyde, acetaldehyde and other aliphatic aldehydes was investigated from May 2008 to June 2011 at 19 locations over a wide area in Japan to survey the pollution level. The pollution level was remarkably controlled by the amount of precipitation. The concentrations of total aliphatic aldehydes and formaldehyde sometimes exceeded 0.6 mg L−1 and 0.2 mg L−1 when the rainfall was small, and decreased rapidly with increasing the amount of rainfall. And in larger rainfall, the concentrations were converged to ca. 0.09 mg L−1 and 0.06 mg L−1 respectively. It was found that the concentration of the pollutants collected in a bottle for a single rainfall event is expressed by an equation based on a dilution model where heavy deposition occurred only at early rainfall followed by continuous dilution of the water with less polluted rainwater. These results were interpreted that the aldehydes in air were washed out very quickly due to their high solubility in water. As progressing of rainfall, the pollution level attained to an equilibrium state between influx and outflux of the pollutants. Precise investigation through a sequential sampling of rainwater by 1 mm during a rainfall event was also performed at several sites. It was found that a break of rainfall is another dominant factor to control the pollution level. A break of rainfall quickly enhanced the pollution level of the resumed rain. Regional difference on rainwater pollution level was observed only at the early stage throughout a rainfall event. The air-pollution levels were high just before beginning rainfall, and they decreased quickly with increasing the amount of rainfall, but never converged to zero. These results suggest that continuous influx of the pollutants occurs in a wide area in Japan besides regional influx.
    Atmospheric Environment 12/2012; 61:588–596. DOI:10.1016/j.atmosenv.2012.05.012 · 3.06 Impact Factor
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    ABSTRACT: The SOS/umu genotoxicity assay evaluates the primary DNA damage caused by chemicals from the β-galactosidase activity of S. typhimurium. One of the weaknesses of the common umu test system based on spectrophotometric detection is that it is unable to measure samples containing a high concentration of colored dissolved organic matters, sediment, and suspended solids. However, umu tests with electrochemical detection techniques prove to be a better strategy because it causes less interference, enables the analysis of turbid samples and allows detection even in small volumes without loss of sensitivity. Based on this understanding, we aim to develop a new umu test system with hydrodynamic chronoamperometry using a rotating disk electrode (RDE) in a microliter droplet. PAPG when used as a substrate is not electroactive at the potential at which PAP is oxidized to p-quinone imine (PQI), so the current response of chronoamperometry resulting from the oxidation of PAP to PQI is directly proportional to the enzymatic activity of S. typhimurium. This was achieved by performing genotoxicity tests for 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2) and 2-aminoanthracene (2-AA) as model genotoxic compounds. The results obtained in this study indicated that the signal detection in the genotoxicity assay based on hydrodynamic voltammetry was less influenced by the presence of colored components and sediment particles in the samples when compared to the usual colorimetric signal detection. The influence caused by the presence of humic acids (HAs) and artificial sediment on the genotoxic property of selected model compounds such as 4-nitroquinoline-N-oxide (4-NQO), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), 1,8-dinitropyrene (1,8-DNP) and 1-nitropyrene (1-NP) were also investigated. The results showed that the genotoxicity of 1-NP and MX changed in the presence of 10 mg∙L-1 HAs. The genotoxicity of tested chemicals with a high hydrophobicity such as 1,8-DNP and 1-NP were decreased substantially with the presence of 1 g∙L-1 sediment. This was not observed in the case of genotoxins with a low log K(ow) value.
    Sensors 12/2012; 12(12):17414-32. DOI:10.3390/s121217414 · 2.05 Impact Factor
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    ABSTRACT: To monitor protein-glycoprotein interactions on magnetic beads, the present study developed an electrochemical assay of the binding between concanavalin A (ConA) and ovalbumin (OVA). The system was a powerful model that could be used to evaluate cell junctions. ConA with an electroactive daunomycin was immobilized on 6 different sizes of magnetic beads (diameter: 1.0-8.9 μm) through a cross-linking agent. Six sizes of OVA-beads (diameter: 1.0-8.9 μm) were also prepared using a similar method. The binding was evaluated using an oxidation peak of ConA with daunomycin because ConA recognized OVA with α-mannose residues. When binding took place on the beads' surface, the peak current was decreased due to the electroactive moieties being covered with OVA. When ConA/daunomycin-OVA binding was evaluated, the change of the peak current obtained by the beads (diameter: 8.9 μm) modified with ConA and daunomycin was the greatest in the presence of OVA-modified beads (diameter: 2.5 μm). In contrast, particle agglomeration was observed for the smallest beads (diameter: 1.0 μm) with ConA/daunomycin and OVA. The results suggested that ConA-OVA binding depended on the size of beads. Thus, this method could be applied to measure protein-glycoprotein interactions on the cell surface.
    The Analyst 07/2012; 137(16):3781-6. DOI:10.1039/c2an35667h · 3.91 Impact Factor
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    ABSTRACT: A paramagnetic microbead-based enzyme immunoassay was demonstrated for detecting ovalbumin (OVA). The immunoassay sandwich was made by attaching a biotinylated antibody to the streptavidin coated beads as a mobile solid phase, capturing antigen, and then exposing the antigen to an antibody conjugated with β-galactosidase. β-Galactosidase converts p-aminophenyl galactopyranoside (PAPG) and fluorescein di-β-D-galactopyranoside (FDG) to p-aminophenol (PAP) and fluorescein, respectively. The current response of PAP generated by the enzymatic reaction of β-galactosidase was detected with hydrodynamic voltammetry in a droplet using a rotating disk electrode (RDE) system. The performance of this electrochemical assay was compared with fluorometric detection of fluorescein produced by the same assay system. The limits of detection for OVA determined by hydrodynamic amperometry and fluorometry were 2.1 nM (43 fmol) and 2.9 nM (58 fmol), respectively. Furthermore, the effects of the conditions commonly found in drinking water supply systems on the OVA assay were also evaluated.
    Analytical methods 05/2012; 4(6):1783-1789. DOI:10.1039/C2AY05738G · 1.94 Impact Factor
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    ABSTRACT: The paramagnetic microbead-based electrochemical binding assay was demonstrated for detecting two kinds of protein simultaneously. The principle of this assay is based on the sequestration electrochemistry. The protein binding electroactive magnetic microbeads which are conjugated with an electroactive compound and a ligand to bind specifically with a target protein were prepared. The avidin-biotin and soybean agglutinin (SBA)-galactosamine were chosen as model protein-ligand systems. The avidin binding electroactive magnetic microbead (ABEMMb) and SBA binding electroactive magnetic microbead (SBEMMb) are constructed by biotin/thionine and galactosamine/ferrocene modified on paramagnetic microbeads. The voltammetric response for these functionalized microbeads was measured by the Nd-Fe-B magnet-incorporating carbon paste rotating disk electrode. The measurements were performed in a microliter droplet using a rotating disk electrode system. Avidin and SBA were simultaneously detected by the decrease in the current responses from the reduction of ABEMMb and SBEMMb that was caused by the binding with target proteins. The limits of detection for avidin and SBA were 4 × 10(-10) and 2 × 10(-10) M, respectively.
    Analytical Sciences 01/2012; 28(1):77. DOI:10.2116/analsci.28.77 · 1.40 Impact Factor
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    ABSTRACT: The influence of halogen substituents on the catalytic oxidation of 2,4,6-trihalogenated phenols (TrXPs) by iron(III)-porphyrin/KHSO₅ catalytic systems was investigated. Iron(III)-5,10,15,20-tetrakis(p-hydroxyphenyl)porphyrin (FeTHP) and its supported variants were employed, where the supported catalysts were synthesized by introducing FeTHP into hydroquinone-derived humic acids via formaldehyde poly-condensation. F (TrFP), Cl (TrCP), Br (TrBP) and I (TrIP) were examined as halogen substituents for TrXPs. Although the supported catalysts significantly enhanced the degradation and dehalogenation of TrFP and TrCP, the oxidation of TrBP and TrIP was not enhanced, compared to the FeTHP catalytic system. These results indicate that the degree of oxidation of TrXPs is strongly dependent on the types of halogen substituent. The order of dehalogenation levels for halogen substituents in TrXPs was F > Cl > Br > I, consistent with their order of electronegativity. The electronegativity of a halogen substituent affects the nucleophilicity of the carbon to which it is attached. The levels of oxidation products in the reaction mixtures were analyzed by GC/MS after extraction with n-hexane. The most abundant dimer product from TrFP via 2,6-difluoroquinone is consistent with a scenario where TrXP, with a more electronegative halogen substituent, is readily oxidized, while less electronegative halogen substituents are oxidized less readily by iron(III)-porphyrin/KHSO₅ catalytic systems.
    Molecules 12/2011; 17(1):48-60. DOI:10.3390/molecules17010048 · 2.10 Impact Factor

Publication Stats

652 Citations
176.61 Total Impact Points


  • 2006–2015
    • University of Toyama
      • Department of Environmental Biology and Chemistry
      Тояма, Toyama, Japan
  • 2005–2013
    • Toyama University
      Тояма, Toyama, Japan
  • 2009
    • Maebashi Institute of Technology
      Maebashi, Gunma Prefecture, Japan
  • 2004–2009
    • University of Cincinnati
      • Department of Chemistry
      Cincinnati, Ohio, United States
  • 2001–2009
    • Gunma University
      • Faculty of Education
      Maebashi-shi, Gunma-ken, Japan
  • 1999–2005
    • Hokkaido University
      • Graduate School of Environmental Science
      Sapporo-shi, Hokkaido, Japan
    • Kitami Institute of Technology
      Notsukeushi, Hokkaidō, Japan